Structural properties of solar flare-producing coronal current system developed in
emerging magnetic flux tube
Coronal activity of magnetic structure formed on the Sun depends on what coronal current system is developed in the structure, which determines how a coronal current
flows in it. To investigate structural properties of the coronal current system responsible for producing a solar flare, we performed a pair of magnetohydrodynamic simulations
of an emerging flux tube, in which the flux tube was composed of strongly/weakly twisted field lines (ST/WT case). By quantitatively evaluating the configuration of coronal current streamlines and applying a fractal dimensional analysis to the spatial distribution of coronal current density in ST case, we demonstrated that
the flare-producing current system relied on a specific coronal current structure of two-dimensional spatiality (current layer or 3D current sheet) where magnetic field locally has a nearly anti-parallel configuration (APMC portion of the current layer). The spatial profile of coronal current passing through the APMC portion may play a key role in three-dimensional magnetic reconnection, a possible mechanism for producing the flare.
We also explained how the degree of field-line twist affected the structural properties of the flare-producing current system by showing how much photospheric current flux reached the corona in ST and WT cases.
Reference
Magara, T.
Publication of Astronomical Society of Japan, 69, 5
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